Program consists of several interrelated clinical, pathophysiological, and pathological studies pertinent to cerebral vascular disease and its therapy. Correlated studies of cerebral circulation cerebral blood volume, and cerebral glucose metabolism will utilize cyclotron produced isotopes and special radiophysical techniques. Evolution of blood coagulation physiological parameters in relation to the clinical course of cerebral vascular occlusion patients will be studied. Related studies are part of a double blind clinical evaluation of urokinase in acute brain infarction cases. Changes in the microcirculation of brain stem of patients who died of cerebral vascular disease are to be studed by special histochemical and electron microscopic techniques. In infants and children prevalence and clinical data are to be gathered on all cerebrovascular patients, with pertinent special studies. Other studies include the pathophysiology of subdural fluid collections pathophysiology of sickle cell disease, and neuropathology of patients with sickle cell anemia and sickle cell trait. Further studies of red cell elasticility in relation to urokinase and other chemical parameters are planned. Bibliographic references: Appraisal of the angiographic circulation time as an index of cerebral blood flow. Gado, M., Eichling, J.O., Grubb, R.L., Jr., Phelps, M.E., Raichle, M.E. and Ter-P@gossian, N.M. Radiol. 115:107, 1975. Raichle, M.E., Eichling, J.O., Gado, M.H., Grubb, R.L. Jr., and Ter-Pogossian, N.M.: Cerebral blood volume in dementia. In Intracranial Pressure II, Lundberg, N., Ponten, U., Brock, M. (eds.), Springer-Verlag, New York, 1975, p. 150.